1. Technical Field
Embodiments of the present invention are related to the field of electronic devices, and in particular, to power supplies for electronic devices.
2. Description of Related Art
It is a common practice in computer and server industry to use several converter stages to convert input alternating current (AC) line voltage into isolated and regulated direct current (DC) voltages, which are supplied to processors, memory, hard drives and like devices. In recent years, interest in high density power conversion has increased substantially. Most of the topologies used for the modern power conversion applications operate in a so-called hard switching mode, in which waveforms of the converter switch have rectangular shapes. Increasing power density in such topologies is primarily based on using faster switching active components (transistors and rectifying diodes) and more compact magnetic components and capacitors. At the same time, the most effective reduction of converter dimensions may be achieved by increasing its switching frequency (permitting reduction in the transformer and filter size). A reason for not employing increased switching frequencies is that high frequency conversion in hard switching topologies is associated with a rise in switching losses, which need larger heatsinks and/or delivery of more cooling air. This significantly hinders an increase in power density. Although the hard switching topology is widely used, power density and cost/size improvements have been achieved by implementing a soft switching (resonant) or zero voltage switching technique, which is characterized by low switching losses.